Folic Acid Inhibitors Flashcards
Short acting sulfonamides
Sulfacetamide
Sulfamethizole
Sulfathiazole
Sulfisoxazole
Sulfachlorpyridazine
Which short-acting sulfonamide is good for opthalmic and topic preparations? Why?
Sulfacetamide (neutral pH)
Which short-acting sulfonamide is good for UTIs in small animals? Why?
Sulfisoxazole (very soluble and rapidly excreted)
Which short-acting sulfonamide is good for respiratory and enteric infections in youngsters (calves, swine)?
Sulfachlorpyridazine
If you wanted to give a short-acting sulfonamide to a calf with enteric infection, what would you give?
Sulfachlorpyridazine in the form of Vetisulid IV injection
Which short-acting sulfonamide is safe in youngsters?
Sulfachlorpyridazine
Intermediate acting sulfonamides
Sulfamethoxazole
Sulfapyridine
Sulfamethazine/sulfadimidine
Sulfadiazine
Which intermediate lasting sulfonamides is used for UTIs in small animals
Sulfamethoxazole
Which two sulfonamides are used to treat UTIs in small animals
Sulfasoxazole
Sulfamethoxazole
Which intermeidate acting sulfonamide is used for prophylactics in drinking water/feed
Sulfamethazine/sulfadimidine
Which intermediate acting sulfonamide is released from a sulfasilazine group?
Sulfapyridine
Long acting sulfonamides
Sulfadimethoxine
Sulfamethazine
Sulfaethoxypyridazine
Enteric sulfonamides
Succinylsulfathiazole
Sulfasalazine
Sulfaquinoxaline
Sulfaguanidine
Phthalylsulfathiazole
Topical sulfonamides
Silver sulfadiazine
Mafenide
Important feature of enteric sulfonamides
Low solubility - poor absorption into systemic circulation.
Good for local action in GIT
Which sulfonamide is used for colitis in dogs
Sulfasalazine
Which sulfonamide is used for coccidiosis in poultry
Sulfaquinoxaline
Immunological toxicity of sulphonamides (2)
- Keratoconjunctivitis sicca (pyridine ring induces hypersensitivity on lacrimal acinar cells)
- Hepatic necrosis (slow acetylation increases production of Hydroxylamine metabolites which are hepatotoxic)
Non-immunological toxicity of sulphonamides (2)
- Nephrotoxicity (due to crystalluria post acetylation. Prevention = hydration, sodium bicarb, vegetarian diet)
- Blood dyscrasias
a. hypothrombinemia
b. aplastic anemia
c. thrombocytopenia
(changes in cell count. Sulfaquinoxoline inhibits vit K epoxide reductase – no vit K, no hepatic clotting factors)
T/F - Non-immunological toxicity of sulphonamides is reversible
Yes!
Blood dyscrasias is reversible by giving Vit K
Which dog breed is sensitive to sulphonamides? What are the sensitivities?
Doberman Pinschers
Polyarthritis
Fever
Cutaneous eruptions
Hepatitis
What can occur in dogs and ducks due to sulphonamide sensitivity
Hypoglycemia
What can potentiated sulfas cause in dogs? Is this reversible?
Iatrogenic hypothyroidism
Targets thyroid peroxidase which synthesizes thyroxine (very reversible)
How do sulphonamides become resistant? (2)
Chromosomal mediated resistance (slow)
Plasmid mediated resistance (fast)
What are three consequences of sulphonamide resistance
- Impaired drug penetration
- Increased PABA production
- Sulfonamide resistant dihydropteroate synthase
What is the efficacy predictor of sulphonamides
Type II (time dependent)
MOA diaminopyrimidines
Reversibly binds/inhibits dihydrofolate (DHF) reductase in bacteria only
(doesnt affect human enzyme)
Which diaminopyrimidine is specific for protozoa
Pyrimethamine
Diamminopyrimidines (6)
‘TOP MAT’
Trimethoprim
Ormetoprim
Pyrimethamine
Metioprim
Aditoprim
Tetroxoprim
T/F Potentiated sulfonamides are bacteristatic
No, CIDAL
Potentiated sulfonamides (5)
- Sulfadiazine + Trimethoprim
- Sulfadoxine + Trimethoprim
- Sulfamethoxazole . Trimethoprim
- Sulfadimethoxine + Ormetoprim
- Sulfaquinoxaline + Pyrimethamine
Which potentiated sulfa is used for horses
Sulfadiazine + Trimethoprim
Which potentiated sulfa is for cows/pigs
Sulfadoxine + Trimethoprim
Which potentiated sulfa is for dogs
Sulfadimethoxine + Ormetoprim
Which potentiated sulfa is best for coccidiosis (and other protozoal infections)
Sulfaquinoxalne + Pyrimethamine
Which antimicrobial class is best for aerobic gram+/gram- and protozoal infections
Potentiated sulfas
How are potentiated sulfas metabolized
Liver:
- Sulfonamides (acetylation, glucuronation)
- Diaminopyrimidines (oxidation and hydroxylation)
T/F potentiated sulfas are well distributed
True - pass into CSF, placenta, milk…
